fix typo: add missing "

Author: hannesm

tuf-spec.md

@@ -823,7 +823,7 @@ Version: **1.0 (Draft)**
    shell-style wildcards.  For example, the path pattern "targets/*.tgz" would
    match file paths "targets/foo.tgz" and "targets/bar.tgz", but not
    "targets/foo.txt".  Likewise, path pattern "foo-version-?.tgz" matches
-   foo-version-2.tgz" and "foo-version-a.tgz", but not "foo-version-alpha.tgz".
+   "foo-version-2.tgz" and "foo-version-a.tgz", but not "foo-version-alpha.tgz".
 
    Prioritized delegations allow clients to resolve conflicts between delegated
    roles that share responsibility for overlapping target paths.  To resolve